This invention relates generally to a process and system for the regeneration of particulate filter traps employed for purifying the exhaust gas of an internal combustion engine, particularly a motor vehicle diesel engine, by oxidation of particulates collected in the traps, combustion of the particulates being initiated by a fuel burner during engine operation.
An exhaust gas treatment system of some type is employed for the reduction of particle emissions from diesel engines. Such systems basically include particulate filter traps which trap and collect the solid portions in the particle phase. The deposited particulates may, however, effect an increase in the flow resistance within the exhaust gas system. This may lead to the creation of increased exhaust gas counterpressures which, depending on the torque and engine rpms, can cause an increase in fuel consumption and, in extreme cases, can lead to engine stall. It therefore becomes necessary to continually or intermittently remove the particulates deposited in the filter trap.
Oxidation of the particulates collected in the filter trap commences at temperatures above 500.degree. to 550.degree. C. By utilizing special catalytic coatings, soot oxidation can be carried out 400.degree. to 450.degree. C. Such high temperatures, however, are achieved by diesel engines only in the upper load range. Effective regeneration of the filter trap is therefore not assured during engine operation.
U.S. Pat. No. 4,481,767 discloses and exhaust gas cleaner and burner system for use with a diesel engine that utilizes a rotatable flame sweep distributor to sequentially direct the flame from a fuel burner across a full inlet face of a filter. Portions of the filter are not intermittently regenerated, but rather only that portion of the filter to be regenerated is intermittently acted upon by the flame for completely burning the soot. The flame jet is thus directed at the inlet face of the filter by a guide mechanism.
U.S. Pat. No. 4,299,600 discloses a trapper device for collecting and incinerating particulates included in the exhaust gas from a diesel engine. Filter traps are located in a pair of transversely separated chambers of the filter unit, and a valve plate is moved for alternately opening either filter trap for receiving the exhaust gas while the other filter trap is closed. The valve plate has a pair of fuel injection nozzles each of which is adapted for communicating a common fuel inlet with one of the traps which is closed by the valve plate.
In both these prior art system no intermittent igniting of the deposited particulates takes place, and in both systems moving parts are required such as guide mechanisms and valve plates for the combustible fuel, and the flames cannnot impinge directly on the deposited particulates for igniting the deposit.